AU1106283A

AU1106283A - Dehydrator

Info

Publication number: AU1106283A
Application number: AU11062/83A
Authority: AU
Inventors: Jose Luis Ruiz-Avila
Original assignee: AKT Consultants Pty Ltd
Current assignee: AKT Consultants Pty Ltd
Priority date: 1982-01-19
Filing date: 1983-01-14
Publication date: 1983-07-28
Anticipated expiration: 2003-01-14
Also published as: JPH0428989B2; BR8305201A; GB8323533D0; JPS59500010A; GB2124350B; GB2124350A; WO1983002495A1; DK412683A; IN159480B; NZ202985A; AU569839B2; US4573278A; DK412683D0

Description

DEHYDRATOR

TECHNICAL FIELD

This invention relates to apparatus for the dehydration of organic material, of the type in which such material is passed from an agitating chamber and through inlet and outlet paths of a dehydrating tower by means of a stream of heated air. Such apparatus is used in the production, for example, of fish meal, and the production of dehydrated meal from various organic raw materials such as meat products, waste materials from poultry and fish processing. BACKGROUND ART

Apparatus of the type referred to is well known in the art, and generally comprises means for the supply of raw material and heated air to an agitator in which the material is partially comminuted and dried until its density is such that it is carried upwardly into a dehydrating tower where final dehydration takes place, the fully treated material being recovered from the air stream beyond the tower by suitable means such as a cyclone. DISCLOSURE OF INVENTION

Equipment of this type known in the prior art suffers from the disadvantage of being incapable of ready adaptation •to different types of feed material, and to feed material of different quality. The object of the present invention is to provide dehydrating apparatus which offers greater flexibility in this regard, by providing apparatus in which the residence time of material within the dehydrator may readily be altered, even during continuous operation. The invention broadly comprises apparatus for the dehydration of organic material in which such material is passed from an agitating chamber, which may alqo provide for comminution of the material, and through inlet and outlet paths of a dehydrating tower by means of a stream of heated air, characterised in that the tower comprises means for

OMPI varying the length of the path of the material therein, thereby to vary the residence time of the material in the tower.

In the preferred embodiment of the invention, the material passes upwardly in the tower and then downwardly on either side of a series of baffles, which may be selectively rotated to vary the height of the path through the tower. BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawings; Fig.l is a rear elevation of a dehydrator embodying the present invention, from the direction 1-1 of Fig.5; Fig.2 is a side elevation of the dehydrator in the direction 2-2 of Fig.5; Fig.3 is a front elevation of the dehydrator in the direction 3-3 of Fig.5; Fig.4 is a side elevation of the dehydrator in the direction 4-4 of Fig.5; Fig.5 is a plan view of the dehydrator; Fig.6 is an ^'end elevation of agitator blades employed in the dehydrator of Figs. 1 to 5; Fig.7 is a plan view of the agitator blades of Fig.6; Fig.8 is an end view of an agitator blade; Fig.9 is an elevation of the baffles employed in the dehydrator of Figs. 1 to 8;

Fig.10 is a further elevation of the baffles; Fig.11 is a plan view of the baffle assembly; Figs.12, 13 and 14 show schematically the baffles in various positions. BEST MODE FOR CARRYING OUT THE INVENTION

The illustrated dehydrator comprises a burner 20 which may be fed with oil or other suitable fuel, to provide by means of a blower (not shown) a stream of hot air to an agitator at 21. The pneumatic flow through the apparatus continues from the agitator 21 via a dehydrating tower 22, a classifier 23, a cyclone 24, exhaust duct 25, an exhaust fan

26 and a flue 27. „

^{^}S.EA\ OMPI Organic material is supplied to the dehydrator from a bin 28 via a screw conveyor 29 driven by a motor 30 to the agitator 21 through a gate 31.

As is well known in the prior art, pneumatic flow through the dehydrator is determined both by the, blower of the burner 20, and the partial vacuum produced by the exhaust fan 26.

The operation of the illustrated dehydrator will now be described in more detail, including those features which exemplify the novel characteristics of the present invention.

Raw material from the conveyor 29 falls through a chute 32 to the gate 31, and thence to the interior of the agitator 21. The gate 31 is controlled by means of a solenoid 33 which is controlled in response to the load on the agitator 21, sensed by means of a current transformer in the supply circuit of the agitator motor (not shown). In this way, a controlled and constant supply of feed is maintained within the agitator 13. Rotating within the cylindrical housing of the agitator 13 on a shaft 34 are two sets of arms 35 (Figs.6, 7 and 8). Each set comprises four arms equally disposed about the shaft 34, and each arm comprises a pair of blades disposed to form a V-shaped cross-section as shown in the end view of Fig. 8, with the free edges of the blades providing sharp cutting edges 36. As the arms 35 rotate within the agitator 21, the material is constantly thrown around and comminuted by the cutting edges 36. Rapid comminution is achieved by the presence of two cutting edges on each arm, and the V-shaped cross-section of the arms facilitates the capture and agitation of the material.

Hot air is supplied to the agitator 13 from the burner 20 through the duct 37, and this is augmented by hot air supplied from the classifier 23 through the duct 38 as referred to below. As the material is comminuted and dried within the agitator 13, its density falls until it reaches a level which is such that the head pressure within the tower 22 allows the material to rise with the flow of hot air into the tower 22.

The tower 22 is cylindrical in shape, and is provided with a central vertical shaft 39. Mounted for rotation on the shaft 39 by means of collars 40 and 41 are a vertically disposed series of baffles 42, 43, 44 and 45. Each of the collars 40 and 41 may rotate independently on the shaft 39, and the topmost collar 41 is coupled with an electric motor 46.

Extending downwardly below the lower edge of each of the baffles 42, 43 and 44, are pairs of lugs 47 and 48 respectively located at positions spaced by 90 in relation to the shaft 39. These lugs extend to a point below the upper edge of the underlying baffle, to engage that baffle as the baffle to which they are attached rotates, as described below. The baffles 42 through 45 function to define the inlet and outlet paths for the hot air and dehydrated material within the tower 22 as shown schematically in Figs. 12, 13 and 14, the lowermost portion of the inlet and outlet flow being defined by a fixed baffle 49. When the baffles are in the position as shown in Fig. 12, hot air and partially dehydrated material enters the tower from the agitator 21 and passes upwardly on the left- hand side (as viewed in Fig. 12) of the fixed baffle 49 and the movable baffles 42 through 45, to pass over the baffle 42 and downwardly to exit from the tower at its lower end on the outlet side of the fixed baffle 49. The motor 46 is arranged to drive the collar 41 in successive quadrants of rotation. Actuation of the motor 46 to move the collar 41 through its first quadrant will cause the baffles to adopt the configuration shown in Fig. 13, with the upper baffle 42 rotated through 90° to a position where it no longer

i PI_ influences the air flow through the tower, shortening the passage through the tower and, therefore, the residence tim of the feed material. When the motor 46 is actuated to rotate the collar 41 through a further quadrant, the lug 47 of the baffle 42 will engage with the baffle 43, rotating i through 90° so that the path through the tower will be further shortened. Continued operation of the motor 46 will ultimately place the baffles in the position shown in Fig. 14, where the minimum path length and minimum residence time is determined by the fixed baffle 49.

Reversal of the motor 46 and continued operation through its quadrants of movement will return the baffles to the maximum residence time condition illustrated in Fig. 12, as the lugs 48 successively engage underlying baffles. In this way, in a typical installation employing a 4 metre tower, the residence time of product within the tower can be varied between 0.5 seconds and 4 seconds. Of course, with greater tower heights, longer residence times can be achieved. The baffles 42 through 45 provide three functions within the tower. They divide the air flow within the single tubular tower, they enable the pneumatic head of the tower to be varied, and also the rotation of the baffles, particularly during their return to the maximum path length condition, permits the clearing from the tower wall of any material which may adhere thereto.

This clearing function may be assisted by the provision of scraping blades 50, mounted on arms 51 disposed at right angles to the lower most baffle 45. Air flow and entrained dehydrated material passes from the tower outlet to the classifier 23, which functions to separate air strata of differing densities in a manner well known in the prior art and not, therefore, described here. The classifier splits the air stream into a stream of hot unsaturated air which is returned to the agitator 21 by the duct 38, and a second stream which contains saturated air

OMPI and the dried solids, this stream being extracted through the manifold 51. If desired, the classifier may be adjusted to direct solids back to the agitator 21 for further drying. The dried solids and saturated air stream pass from the manifold 51, upwardly through a duct 52 to the cyclone

24. Dried solids are removed from the cyclone 24 at the air lock 53, while saturated air passes from the cyclone, through the duct 25 to the exhaust fan 26, whence it is discharged to atmosphere by means of the flue 27. As in prior art dehydrators, the heat input may be varied by control of the burner 20, and this combined with the great flexibility of residence time achieved by the adjustable baffles, enables the dehydrator of the present invention to operate satisfactorily with a great range of raw material without extensive modification, as would be required in the prior art.

While the invention has been described herein in relation to its preferred mode of realisation, it will be appreciated that the general principles of novelty which have been disclosed, are capable of application in other ways, and the invention is not, therefore, to be regarded as restricted by the particularity of the preceding description.

For example, instead of mounting the baffles for rotation about a vertical axis, the baffles may be mounted on individual horizontal axis. Other arrangements whereby the baffles may be successively rendered inoperative, will be apparent to the skilled reader.

Claims

1. Apparatus for the dehydration of organic material in which the material is passed from an agitating chamber and through inlet and outlet paths of a dehydrating tower by means of a stream of heated air, ^■. characterised in that said tower comprises means for varying the length of the path of said material therein, thereby to vary the residence time of said material in said tower.

2. Apparatus according to Claim 1 further characterised in that said stream passes upwardly in said tower and then downwardly to exit therefrom.

3. Apparatus according to Claim 2 further characterised in that the path of said stream is defined by a series of vertically disposed baffles mounted within said tower.

4. Apparatus according to Claim^' 3 wherein said baffles may be aligned in a common plane between the entry and exit of said stream, such that said path proceeds upwardly on one side of said plane, above the highest baffle, and downwardly to said exit on the other side of said plane.

5. Apparatus according to Claim 4 further characterised in that said baffles are so mounted as to be individually movable out of said plane.

6. Apparatus according to Claim 5 further comprising driving means associated with said baffles, said driving means being actuatable to a first extent to move the highest baffle out of said plane to an inoperative position so that the height of said stream is defined by the second highest baffle.

7. Apparatus according to Claim 6 wherein actuation of said driving means to a second extent causes movement of the second highest baffle out of said plane to an inoperative position so that the height of said path is determined by the third highest baffle.

8. Apparatus according to Claim 5 further characterised in that said baffles are mounted for individual rotation about a vertical axis.

9. Apparatus according to Claim 1 wherein said agitator comprises a plurality of arms.mounted radially on a rotating shaft, each said arm comprising a pair of parallel blades, said blades being mutually obliquely disposed to present a V-shape in a cross-section parallel to said shaft, the free edges of said blades comprising cutting edges directed in the direction of rotation of said shaft.

OMPI